Chapter 9
Preview
•
•
•
•
•
•
Lesson Starter
Objective
Stoichiometry Definition
Reaction Stoichiometry Problems
Mole Ratio
Stoichiometry Calculations
Chapter 9
Section 1 Introduction to
Stoichiometry
Lesson Starter
Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g)
• If 2 mol of HCl react, how many moles of H2 are obtained?
• How many moles of Mg will react with 2 mol of HCl?
• If 4 mol of HCl react, how many mol of each product are
produced?
• How would you convert from moles of substances to
masses?
Chapter 9
Section 1 Introduction to
Stoichiometry
Objective
• Define stoichiometry.
• Describe the importance of the mole ratio in
stoichiometric calculations.
• Write a mole ratio relating two substances in a
chemical equation.
Chapter 9
Section 1 Introduction to
Stoichiometry
Stoichiometry Definition
• Composition stoichiometry deals with the mass
relationships of elements in compounds.
• Reaction stoichiometry involves the mass
relationships between reactants and products in a
chemical reaction.
Chapter 9
Section 1 Introduction to
Stoichiometry
Reaction Stoichiometry Problems
Problem Type 1: Given and
unknown quantities are amounts
in moles.
Amount of given
substance (mol)
Problem Type 2: Given is an
amount in moles and unknown is
a mass
Amount of given
substance (mol)
Amount of unknown
substance (mol)
Amount of unknown
substance (mol)
Mass of unknown
substance (g)
Chapter 9
Section 1 Introduction to
Stoichiometry
Reaction Stoichiometry Problems, continued
Problem Type 3: Given is a
mass and unknown is an amount
in moles.
Mass of given
substance (g)
Amount of given
substance (mol)
Amount of unknown
substance (mol)
Problem Type 4: Given is a mass
and unknown is a mass.
Mass of a given substance (g)
Amount of given
substance (mol)
Amount of unknown
substance (mol)
Mass of unknown
substance (g)
Chapter 9
Section 1 Introduction to
Stoichiometry
Mole Ratio
• A mole ratio is a conversion factor that relates the
amounts in moles of any two substances involved in a
chemical reaction
Example:
2Al2O3(l) → 4Al(s) + 3O2(g)
Mole Ratios: 2 mol Al2O3
4 mol Al
,
2 mol Al2O3
3 mol O2
, 4 mol Al
3 mol O2
Chapter 9
Section 1 Introduction to
Stoichiometry
Converting Between Amounts in Moles
Chapter 9
Stoichiometry
Calculations
Section 1 Introduction to
Stoichiometry
Chapter 9
Section 2 Ideal Stoichiometric
Calculations
Preview
• Lesson Starter
• Objective
• Conversions of Quantities in Moles
• Conversions of Amounts in Moles to Mass
• Mass-Mass to Calculations
• Solving Various Types of Stoichiometry Problems
Chapter 9
Section 2 Ideal Stoichiometric
Calculations
Lesson Starter
Acid-Base Neutralization Reaction Demonstration
• What is the equation for the reaction of HCl with
NaOH?
• What is the mole ratio of HCl to NaOH?
Chapter 9
Section 2 Ideal Stoichiometric
Calculations
Objective
• Calculate the amount in moles of a reactant or a
product from the amount in moles of a different
reactant or product.
• Calculate the mass of a reactant or a product from the
amount in moles of a different reactant or product.
Chapter 9
Section 2 Ideal Stoichiometric
Calculations
Objectives, continued
• Calculate the amount in moles of a reactant or a
product from the mass of a different reactant or
product.
• Calculate the mass of a reactant or a product from the
mass of a different reactant or product.
Chapter 9
Section 2 Ideal Stoichiometric
Calculations
Conversions of Quantities in Moles
Chapter 9
Solving
Mass-Mass
Stoichiometry
Problems
Section 2 Ideal Stoichiometric
Calculations
Chapter 9
Section 2 Ideal Stoichiometric
Calculations
Conversions of Quantities in Moles, continued
Sample Problem A
In a spacecraft, the carbon dioxide exhaled by astronauts
can be removed by its reaction with lithium hydroxide, LiOH,
according to the following chemical equation.
CO2(g) + 2LiOH(s) → Li2CO3(s) + H2O(l)
How many moles of lithium hydroxide are required to react
with 20 mol CO2, the average amount exhaled by a person
each day?
Chapter 9
Section 2 Ideal Stoichiometric
Calculations
Conversions of Quantities in Moles, continued
Sample Problem A Solution
CO2(g) + 2LiOH(s) → Li2CO3(s) + H2O(l)
Given: amount of CO2 = 20 mol
Unknown: amount of LiOH (mol)
Solution:
mol ratio
m
o
l
L
i
O
H
m
o
l
C
O


m
o
l
L
i
O
H
2
m
o
l
C
O
2
2
m
o
l
L
i
O
H
2
0
m
o
l
C
O


4
0
m
o
l
L
i
O
H
2
1
m
o
l
C
O
2
Chapter 9
Section 2 Ideal Stoichiometric
Calculations
Conversions of Amounts in Moles to Mass
Chapter 9
Section 2 Ideal Stoichiometric
Calculations
Solving Stoichiometry
Problems with Moles
or Grams
Chapter 9
Section 2 Ideal Stoichiometric
Calculations
Conversions of Amounts in Moles to Mass,
continued
Sample Problem B
In photosynthesis, plants use energy from the sun to
produce glucose, C6H12O6, and oxygen from the
reaction of carbon dioxide and water.
What mass, in grams, of glucose is produced when
3.00 mol of water react with carbon dioxide?
Chapter 9
Section 2 Ideal Stoichiometric
Calculations
Conversions of Amounts in Moles to Mass, continued
Sample Problem B Solution
Given: amount of H2O = 3.00 mol
Unknown: mass of C6H12O6 produced (g)
Solution:
Balanced Equation: 6CO2(g) + 6H2O(l) → C6H12O6(s) + 6O2(g)
mol ratio
molar mass factor
m
o
l
C
H
O
g
C
H
O
6
1
2
6
6
1
2
m
o
l
H
O

 6
g
C
H
O
2
6
1
2
6
m
o
l
H
O
m
o
l
C
H
O
2
6
1
2
6
1
m
o
l
C
H
O
8
0
.
1
8
g
C
H
O
6
1
2
61
6
1
2
6
3
.
0
0
m
o
l
H
O


=
2
6
m
o
l
H
O
1
m
o
l
C
H
O
2
6
1
2
6
90.1 g C6H12O6
Chapter 9
Section 2 Ideal Stoichiometric
Calculations
Conversions of Mass to Amounts in Moles
Chapter 9
Section 2 Ideal Stoichiometric
Calculations
Conversions of Mass to Amounts in Moles,
continued
Sample Problem D
The first step in the industrial manufacture of nitric acid
is the catalytic oxidation of ammonia.
NH3(g) + O2(g) → NO(g) + H2O(g) (unbalanced)
The reaction is run using 824 g NH3 and excess
oxygen.
a. How many moles of NO are formed?
b. How many moles of H2O are formed?
Chapter 9
Section 2 Ideal Stoichiometric
Calculations
Conversions of Mass to Amounts in Moles, continued
Sample Problem D Solution
Given: mass of NH3 = 824 g
Unknown:
a. amount of NO produced (mol)
b. amount of H2O produced (mol)
Solution:
Balanced Equation: 4NH3(g) + 5O2(g) → 4NO(g) + 6H2O(g)
molar mass factor
mol ratio
a.
m
o
l
N
H
m
o
l
N
O
3
g
N
H



m
o
l
N
O
3
g
N
H
m
o
l
N
H
3
3
b.
m
o
l
N
H
o
l
H
O
3 m
2
g
N
H



m
o
l
H
O
3
2
g
N
H
m
o
l
N
H
3
3
Chapter 9
Section 2 Ideal Stoichiometric
Calculations
Conversions of Mass to Amounts in Moles,
continued
Sample Problem D Solution, continued
molar mass factor
mol ratio
1
m
o
l
N
H
m
o
l
N
O
3 4


4
8
.
4
m
o
l
N
O
1
7
.
0
4
g
N
H
m
o
l
N
H
3 4
3
2
4
g
N
H

a. 8
3
1
m
o
l
N
H
m
o
l
H
O
3 6
 2

7
2
.
5
m
o
l
H
O
2
1
7
.
0
4
g
N
H
m
o
l
N
H
34
3
2
4
g
N
H

b. 8
3
Chapter 9
Section 2 Ideal Stoichiometric
Calculations
Mass-Mass to Calculations
Chapter 9
Section 2 Ideal Stoichiometric
Calculations
Solving Mass-Mass Problems
Chapter 9
Section 2 Ideal Stoichiometric
Calculations
Mass-Mass to Calculations, continued
Sample Problem E
Tin(II) fluoride, SnF2, is used in some toothpastes. It is
made by the reaction of tin with hydrogen fluoride
according to the following equation.
Sn(s) + 2HF(g) → SnF2(s) + H2(g)
How many grams of SnF2 are produced from the
reaction of 30.00 g HF with Sn?
Section 2 Ideal Stoichiometric
Calculations
Chapter 9
Mass-Mass to Calculations, continued
Sample Problem E Solution
Given: amount of HF = 30.00 g
Unknown: mass of SnF2 produced (g)
Solution:
molar mass factor
mol ratio
molar mass factor
m
o
l
S
n
F
S
n
F
m
o
l
H
F
2 g
g
H
F
 
2
g
S
n
F
2
g
H
F
m
o
l
H
F
m
o
l
S
n
F
2
1
m
o
l
S
n
F
5
6
.
7
1
g
S
n
F
1
m
o
l
H
F
21
2
g
H
F



2
0
.
0
1
g
H
F
2
m
o
l
H
F
1
m
o
l
S
n
F
2
= 117.5 g SnF2
Chapter 9
Section 2 Ideal Stoichiometric
Calculations
Solving Various Types of Stoichiometry Problems
Chapter 9
Section 2 Ideal Stoichiometric
Calculations
Solving Various Types of Stoichiometry Problems
Chapter 9
Section 2 Ideal Stoichiometric
Calculations
Solving Volume-Volume
Problems
Chapter 9
Section 2 Ideal Stoichiometric
Calculations
Solving Particle Problems
Chapter 9
Section 3 Limiting Reactants and
Percentage Yield
Preview
• Objectives
• Limiting Reactants
• Percentage Yield
Chapter 9
Section 3 Limiting Reactants and
Percentage Yield
Objectives
• Describe a method for determining which of two reactants is a
limiting reactant.
• Calculate the amount in moles or mass in grams of a product,
given the amounts in moles or masses in grams of two
reactants, one of which is in excess.
• Distinguish between theoretical yield, actual yield, and
percentage yield.
• Calculate percentage yield, given the actual yield and
quantity of a reactant.
Chapter 9
Section 3 Limiting Reactants and
Percentage Yield
Limiting Reactants
• The limiting reactant is the reactant that limits the
amount of the other reactant that can combine and the
amount of product that can form in a chemical reaction.
• The excess reactant is the substance that is not used
up completely in a reaction.
Chapter 9
Section 3 Limiting Reactants and
Percentage Yield
Limited Reactants, continued
Sample Problem F
Silicon dioxide (quartz) is usually quite unreactive but
reacts readily with hydrogen fluoride according to the
following equation.
SiO2(s) + 4HF(g) → SiF4(g) + 2H2O(l)
If 6.0 mol HF is added to 4.5 mol SiO2, which is the
limiting reactant?
Chapter 9
Section 3 Limiting Reactants and
Percentage Yield
Limited Reactants, continued
Sample Problem F Solution
SiO2(s) + 4HF(g) → SiF4(g) + 2H2O(l)
Given: amount of HF = 6.0 mol
amount of SiO2 = 4.5 mol
Unknown: limiting reactant
Solution:
mole ratio
m
o
l
S
i
F
m
o
l
H
F
 4

m
o
l
S
i
F
p
r
o
d
u
c
e
d
4
m
o
l
H
F
m
o
l
S
i
F
4
m
o
l
S
i
O


m
o
l
S
i
F
p
r
o
d
u
c
e
d
2
4
m
o
l
S
i
O
2
Chapter 9
Section 3 Limiting Reactants and
Percentage Yield
Limited Reactants, continued
Sample Problem F Solution, continued
SiO2(s) + 4HF(g) → SiF4(g) + 2H2O(l)
1
m
o
l
S
i
F
4
4
.
5
m
o
l
S
i
O


4
.
5
m
o
l
S
i
F
p
r
o
d
u
c
e
d
2
4
1
m
o
l
S
i
O
2
1
m
o
l
S
i
F
6
.
0
m
o
l
H
F
 4

1
.
5
m
o
l
S
i
F
p
r
o
d
u
c
e
d
4
4
m
o
l
H
F
HF is the limiting reactant.
Chapter 9
Section 3 Limiting Reactants and
Percentage Yield
Percentage Yield
• The theoretical yield is the maximum amount of
product that can be produced from a given amount of
reactant.
• The actual yield of a product is the measured amount
of that product obtained from a reaction.
• The percentage yield is the ratio of the actual yield to
the theoretical yield, multiplied by 100.
a
c
t
u
a
l
y
i
e
l
d
p
e
r
c
e
n
t
a
g
e
y
i
e
l
d


1
0
0
t
h
e
o
r
e
c
t
i
c
a
l
y
i
e
l
d
Chapter 9
Section 3 Limiting Reactants and
Percentage Yield
Percentage Yield, continued
Sample Problem H
Chlorobenzene, C6H5Cl, is used in the production of
many important chemicals, such as aspirin, dyes, and
disinfectants. One industrial method of preparing
chlorobenzene is to react benzene, C6H6, with chlorine,
as represented by the following equation.
C6H6 (l) + Cl2(g) → C6H5Cl(l) + HCl(g)
When 36.8 g C6H6 react with an excess of Cl2, the
actual yield of C6H5Cl is 38.8 g.
What is the percentage yield of C6H5Cl?
Chapter 9
Section 3 Limiting Reactants and
Percentage Yield
Percentage Yield, continued
Sample Problem H Solution
C6H6 (l) + Cl2(g) → C6H5Cl(l) + HCl(g)
Given:
mass of C6H6 = 36.8 g
mass of Cl2 = excess
actual yield of C6H5Cl = 38.8 g
Unknown: percentage yield of C6H5Cl
Solution:
Theoretical yield
molar mass factor
mol ratio
molar mass
m
o
l
C
H
o
l
C
H
C
l g
C
H
C
l
6
6m
6
5
6
5
g
C
H
 


g
C
H
C
l
6
6
6
5
g
C
H
m
o
l
C
H
o
l
C
H
C
l
6
6
6
6m
6
5
Chapter 9
Section 3 Limiting Reactants and
Percentage Yield
Percentage Yield, continued
Sample Problem H Solution, continued
C6H6(l) + Cl2(g) → C6H5Cl(l) + HCl(g)
Theoretical yield
1
m
o
l
C
H
1
m
o
l
C
H
C
l 1
1
2
.
5
6
g
C
H
C
l
6
6
6
5
6
5
3
6
.
8
g
C
H



6
6
7
8
.
1
2
g
C
H
m
o
l
C
H
1
m
o
l
C
H
C
l
6
6 1
6
6
6
5

5
3
.
0
g
C
H
C
l
6
5
Percentage yield
a
c
t
u
a
l
y
i
e
l
d
p
e
r
c
e
n
t
a
g
e
y
i
e
l
d
C
H
C
l


1
0
0
6
5
t
h
e
o
r
e
c
t
i
c
a
l
y
i
e
l
d
3
8
.
8
g
p
e
r
c
e
n
t
a
g
e
y
i
e
l
d
 
1
0
0
7
3
.
2
%
5
3
.
0
g